Philip Ball

www.philipball.com

Utopia TheoryTowards a physics of

society

“The centre of politics has shifted…. The neoliberal thinking that has dominated the industrial world for nearly 30 years has led to a financial crisis, which in turn caused the global downturn…. Clearly, there can be no turning back to the failed and discredited politics of old. Instead, we need to use this time of emergency to aim for a different future and to get there by different means…. this is not a crisis of capitalism, but a crisis of a society and democracy that have failed to regulate the market.”

Neal Lawson & John Harris, New Statesman 9 March 2009

“Many of the problems our economy faces are the result of the use of misguided models. Unfortunately, too many [economic policy-makers] took the overly simplistic models of courses in the principles of economics (which typically assume perfect information) and assumed they could use them as a basis for economic policy… We need a new balance between market and government.”

Joseph Stiglitz, New Statesman 16 October 2008

Social Physics and the Complex Systems of Human Social Dynamics

N. Johnson, Two’s Company, Three Is Complexity (OneWorld, 2007) M. Buchanan, The Social Atom (Bloomsbury, 2007); Ubiquity (Weidenfeld & Nicolson, 2000) P. Ball, Critical Mass (Heinemann, 2004) C. Castellano & S. Fortunato, Rev. Mod. Phys. 81 (Jan-Mar 2009) J. H. Miller & S. E. Page, Complex Adaptive Systems (Princeton University Press, 2007) J. M. Epstein, Generative Social Science (Princeton University Press, 2006)

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Year

Average

Average Number of deaths

Pro

bab

ilit

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f th

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Death statistics

1510501005000.000010.00010.010.0010.11Firm size (number of employees)

Fre

que

ncy

of f

irm

s o

f th

at s

ize

US firms in 1997

Axtell, Science 293, 1818 (2001)

Gaussian

Power law

110100100010,000110101010-2-4-6-8

Number of connections kPro

babi

lity

of h

avin

g k

conn

ectio

ns

Connections of pages on the WWW

Albert et al., Nature 401, 130 (1999).

Probability distribution of towns around London

1000100100.0010.010.1110100

Area (square km)

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mb

er

of to

wn

s

Makse et al., Nature 377, 608 (1995).

Wealth distribution in the UK, 1996

1010010000.1110100Total net capital (thousands of pounds)

Cu

mu

lativ

e p

erce

nta

ge o

f pop

ula

tion

Pareto law

Statistics of fatal conflicts

Fatalities

Nu

mb

er

of c

on

flict

s

1000100101100100010,000100,0001 million10 millionL. F. Richardson, Statistics of Deadly Quarrels, eds Q. Wright & C. C. Lienau (Boxwood Press, Pittsburgh, 1960)

Statistics of fatal conflicts

Fatalities

Nu

mb

er

of c

on

flict

s

1000100101100100010,000100,0001 million10 millionN. Johnson et al., arxiv/physics/0506213

Queuing and task allocation

J. G. Oliveira & A.-L. Barabási,Nature 437, 1251 (2005)

Voting statistics in the Brazilian elections, 1998

Fraction of total votes

Nu

mb

er

of c

an

did

ate

s

0.00010.0010.010.10.00001Costa Filho et al., Phys. Rev. E 60, 1067 (1999).

Social power laws and self-organized criticalityG. K. Zipf, Human Behavior and the Principle of Least Effort (Addison-Wesley, Reading, MA, 1949)

Self-organized criticality and the sandpile0.10.010.0010.000111010010003210-4-3-2-10.00001-5

Size of avalanche

Pro

bab

ility

of a

vala

nch

eFluctuations at the critical point

Economic fluctuations

10010.01100.10.001-15-10-505101520-20Variation

-20-1001020-20-1001020ab S&P500

Gaussian

‘Fat-tailed’

The magnetism of voting

0.00010.0010.010.10.00001A. T. Bernardes et al., Eur. Phys. J. B 25, 123 (2002)

Opinion dynamics

K. Sznajd-Weron & J. Sznajd, Int. J. Mod. Phys. C 11, 1157 (2000)

The rules of opinion formation (Sznajd model)

W. Weidlich, Sociodynamics (Taylor & Francis, 2002)S. Galam et al., J. Math. Sociol. 9, 1 (1982)

“…there is an unbridgeable gap between the ‘behaviour’ of [subatomic particles] and those of the human beings who constitute the objects of study of social science... aside from pure physical reflexes, human behaviour cannot be understood without the concept of volition—the unpredictable capacity to change our minds up to the very last moment. By way of contrast, the elements of nature ‘behave’ as they do for reasons of which we know only one thing: the particles of physics do not ‘choose’ to behave as they do.”

Robert Heilbroner

Feedback in social interactions

A rare example of ‘turning the dial’ experimentally: M. J. Salganik et al., Science 311, 854 (2006)

The ‘Broken Windows’ effect: K. Keizer et al., Science 322, 1681 (2008)

Attraction and repulsion in human interaction

D. Helbing & P. Molnar, Phys. Rev. E 51, 4282 (1995)

Interacting walkers in a corridor

D. Helbing et al., Environment & Planning B, 28, 361 (2001).

http://www.helbing.org/Pedestrians/Corridor.html

Interacting walkers in a panic

D. Helbing et al., Nature 407, 487 (2000).http://angel.elte.hu/~panic/

Interacting walkers at the Notting Hill Carnival

M. Batty et al., Urban Studies 40, 1573 (2003).

Interacting walkers at the Notting Hill Carnival

M. Batty et al., Urban Studies 40, 1573 (2003).

The formation of human trailsD. Helbing et al., Nature 388, 47 (1997)

The formation of human trails

The formation of human trails

The formation of human trails

Modelling traffic

D. Helbing, Rev. Mod. Phys. 73, 1067 (2001)B. S. Kerner, The Physics of Traffic (Springer, 2004)

Phantom traffic jams?

Time

Dis

tanc

e al

ong

road

Phasetransitions

Density

Vapour

Open road

Liquid

Congested

Solid

Jam

*

*

*

*

Why do societies segregate?

T. C. Schelling, Micromotives and Macrobehavior (W. W. Norton, New York, 1978)

0 10 20 30 40 50

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Alliance formation

Alliance 1SunAT&TPrimeIBM

≈ UNIX International(+IBM)

Alliance 2DECHewlett-PackardApolloIntergraphSGI

≈ Open Software Foundation

(-IBM)

R. Axelrod et al., Management Sci. 41, 1493 (1995)R. Axelrod & D. S. Bennett, Brit. J. Polit. Sci. 23, 211 (1993)

ABCD ABCD

Firm growth

R. Axtell, Working Paper No. 3, Brookings Institution, Washington (1999)

100150200250200400600

200150100502004006008001000TimeTimea b

Num

ber

of f

irm

s

Firm turnover

1510501005000.000010.00010.010.0010.11a b10,000,0001,000,000100,00010,0001,0001001101001,00010,000100,0001,000,000Firm size (number of employees)Firm size (number of employees)

Fre

quen

cy o

f fi

rms

of th

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ize

Simulated distributionfrom agent-based model

R. Axtell, Science 293, 1818 (2001)

10,000,0001,000,000100,00010,0001,0001001101001,00010,000100,0001,000,000Firm size (number of employees)Num

ber

of f

irm

s

Game theory

e.g. the Minority Game: D. Challet, M. Marsili & Y.-C. Zhang, Minority Games (Oxford University Press, 2005)

Econophysics

R. N. Mantegna & H. E. Stanley, Introduction to Econophysics (Cambridge University Press, 2000)

J. L. McCauley, Dynamics of Markets (Cambridge University Press, 2004)

J. D. Farmer & J. Geanakoplos, arxiv:0803.2996

Thomas Hobbes(1588-1679)

The first ‘social physicist’?

Leviathan (1651)

John Stuart Mill(1806-73)

Auguste Comte(1798-1857)

Pierre-Simon Laplace(1749-1827)

The emergence of social physics